utun2/src/packet_dump.c

#include "packet_dump.h"
#include "../lib/debug_config.h"
#include <stdio.h>
#include <string.h>

static const char* tcp_flags_to_str(uint8_t flags) {
    static char buf[32];
    int pos = 0;
    buf[0] = '\0';
    
    if (flags & 0x01) { pos += snprintf(buf + pos, sizeof(buf) - pos, "FIN,"); }
    if (flags & 0x02) { pos += snprintf(buf + pos, sizeof(buf) - pos, "SYN,"); }
    if (flags & 0x04) { pos += snprintf(buf + pos, sizeof(buf) - pos, "RST,"); }
    if (flags & 0x08) { pos += snprintf(buf + pos, sizeof(buf) - pos, "PSH,"); }
    if (flags & 0x10) { pos += snprintf(buf + pos, sizeof(buf) - pos, "ACK,"); }
    if (flags & 0x20) { pos += snprintf(buf + pos, sizeof(buf) - pos, "URG,"); }
    if (flags & 0x40) { pos += snprintf(buf + pos, sizeof(buf) - pos, "ECE,"); }
    if (flags & 0x80) { pos += snprintf(buf + pos, sizeof(buf) - pos, "CWR,"); }
    
    if (pos > 0 && buf[pos - 1] == ',') {
        buf[pos - 1] = '\0';
    }
    
    if (buf[0] == '\0') {
        return "none";
    }
    return buf;
}

char* dump_ip_packet_to_buffer(const uint8_t* data, size_t len) {
    static char buffer[1024];
    buffer[0] = '\0';

    if (len < 20) {
        snprintf(buffer, sizeof(buffer), "Packet too small: %zd bytes", len);
        return buffer;
    }

    uint8_t version = (data[0] >> 4) & 0x0F;
    if (version != 4) {
        snprintf(buffer, sizeof(buffer), "Non-IPv4 packet: %zd bytes", len);
        return buffer;
    }

    uint8_t ihl = (data[0] & 0x0F) * 4;
    if (len < ihl) {
        snprintf(buffer, sizeof(buffer), "Truncated IP header: %zd bytes", len);
        return buffer;
    }

    uint8_t protocol = data[9];
    uint32_t src_ip = *(uint32_t*)&data[12];
    uint32_t dst_ip = *(uint32_t*)&data[16];

    char src_str[16], dst_str[16];
    snprintf(src_str, sizeof(src_str), "%u.%u.%u.%u",
             (src_ip) & 0xFF, (src_ip >> 8) & 0xFF,
             (src_ip >> 16) & 0xFF, (src_ip >> 24) & 0xFF);
    snprintf(dst_str, sizeof(dst_str), "%u.%u.%u.%u",
             (dst_ip) & 0xFF, (dst_ip >> 8) & 0xFF,
             (dst_ip >> 16) & 0xFF, (dst_ip >> 24) & 0xFF);

    const char* proto_name = "UNKNOWN";
    uint16_t src_port = 0, dst_port = 0;
    char proto_info[128] = {'\0'};
    int is_special_proto = 0;

    if (protocol == 6 && len >= ihl + 20) {
        proto_name = "TCP";
        src_port = (data[ihl] << 8) | data[ihl + 1];
        dst_port = (data[ihl + 2] << 8) | data[ihl + 3];
        
        uint32_t seq_num = ((uint32_t)data[ihl + 4] << 24) |
                           ((uint32_t)data[ihl + 5] << 16) |
                           ((uint32_t)data[ihl + 6] << 8) |
                           ((uint32_t)data[ihl + 7]);
        uint32_t ack_num = ((uint32_t)data[ihl + 8] << 24) |
                           ((uint32_t)data[ihl + 9] << 16) |
                           ((uint32_t)data[ihl + 10] << 8) |
                           ((uint32_t)data[ihl + 11]);
        uint8_t flags = data[ihl + 13];
        uint16_t window = (data[ihl + 14] << 8) | data[ihl + 15];
        
        snprintf(proto_info, sizeof(proto_info), "[%s] seq=%u ack=%u win=%u",
                 tcp_flags_to_str(flags), seq_num, ack_num, window);
        is_special_proto = 1;
        
    } else if (protocol == 17 && len >= ihl + 8) {
        proto_name = "UDP";
        src_port = (data[ihl] << 8) | data[ihl + 1];
        dst_port = (data[ihl + 2] << 8) | data[ihl + 3];
        uint16_t udp_len = (data[ihl + 4] << 8) | data[ihl + 5];
        
        snprintf(proto_info, sizeof(proto_info), "len=%u", udp_len);
        is_special_proto = 1;
        
    } else if (protocol == 1 && len >= ihl + 8) {
        proto_name = "ICMP";
        uint8_t icmp_type = data[ihl];
        uint16_t icmp_id = (data[ihl + 4] << 8) | data[ihl + 5];
        uint16_t icmp_seq = (data[ihl + 6] << 8) | data[ihl + 7];
        if (icmp_type == 0) {
            snprintf(proto_info, sizeof(proto_info), "echo_reply seq=%u id=%u", icmp_seq, icmp_id);
        } else if (icmp_type == 8) {
            snprintf(proto_info, sizeof(proto_info), "echo_request seq=%u id=%u", icmp_seq, icmp_id);
        } else {
            snprintf(proto_info, sizeof(proto_info), "type=%u code=%u", icmp_type, data[ihl + 1]);
        }
        is_special_proto = 1;
    }

    if (is_special_proto && proto_info[0] != '\0') {
        if (src_port > 0 && dst_port > 0) {
            int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s:%d -> %s:%d (%zd bytes) %s",
                        proto_name, src_str, src_port, dst_str, dst_port, len, proto_info);
            if (offset > 0 && offset < (int)sizeof(buffer) - 50) {
                snprintf(buffer + offset, sizeof(buffer) - offset, " data: "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x",
                    data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3],
                    data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7],
                    data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11],
                    data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15],
                    data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19],
                    data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23],
                    data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27],
                    data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]);
            }
        } else {
            int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s -> %s (%zd bytes) %s",
                        proto_name, src_str, dst_str, len, proto_info);
            if (offset > 0 && offset < (int)sizeof(buffer) - 50) {
                snprintf(buffer + offset, sizeof(buffer) - offset, " data: "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x",
                    data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3],
                    data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7],
                    data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11],
                    data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15],
                    data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19],
                    data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23],
                    data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27],
                    data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]);
            }
        }
    } else {
        int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s:%d -> %s:%d (%zd bytes) data: "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x "
                    "%02x%02x%02x%02x%02x%02x%02x%02x",
                    proto_name, src_str, src_port, dst_str, dst_port, len,
                    data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3],
                    data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7],
                    data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11],
                    data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15],
                    data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19],
                    data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23],
                    data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27],
                    data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]);
        if (offset > 0 && offset < (int)sizeof(buffer)) {
            buffer[offset] = '\0';
        }
    }

    return buffer;
}